The invention generally relates to apparatus and methods for determining both the permeability and the diffusivity of a porous solid.
Permeability is one of the most commonly measured properties of porous materials. It is the ease at which a fluid is able to flow through the material when a pressure gradient is applied or essentially the fluid conductivity of a porous material. Ishizaki et al. (1998) Porous materials; process technology and applications shows that measurements of permeability can provide information about the pore structure and the tortuosity of interconnected pores within a sample.
The prior art discloses a variety of methods and apparatus by which permeability of a porous solid sample is measured. These include the use of wetting liquids for the determination of permeability, permeability from mercury porosimetry, laser-polarised gas nuclear magnetic resonance for permeability measurements and image analysis for permeability prediction.
The diffusivity of a porous material is also a useful property to measure as it provides information on tortuosity as well as pore length. The prior art also discloses methods and apparatus for measuring this property.
It is an object of the invention to provide an improved way of measuring the permeability and diffusivity of a porous solid.